1. Field of the Invention
The present invention relates, generally, to a polishing pad conditioner and a chemical mechanical polishing apparatus having the polishing pad conditioner. More particularly, the present invention relates to a polishing pad conditioner of a chemical and mechanical polishing apparatus that is used for planarizing a surface of a semiconductor substrate.
2. Description of the Related Art
To meet various demands of consumers, technologies for manufacturing semiconductor devices have been developed to improve the quality, e.g., integration degree, reliability, response speed, etc., of semiconductor devices. Generally, a semiconductor device is manufactured using multiple processes including deposition, photolithography, etching, implantation, and polishing processes, etc. The polishing process plays an important role to improve structural stability and electrical characteristics of the semiconductor device. And consequently, planarizing has become increasingly more important.
In general, a chemical mechanical polishing (CMP) process is widely used to planarize a surface of a layer formed on the semiconductor substrate. The CMP process uses both chemical reactions between a slurry and the surface of the layer and mechanical frictions between a circular polishing pad and the surface of the layer to planarize the surface of the layer formed on the semiconductor substrate.
A CMP apparatus for carrying out the CMP process includes a circular polishing pad disposed on a polishing table, a polishing head for holding and rotating the semiconductor substrate, a slurry supply unit for supplying the slurry at an interface between a surface of the semiconductor substrate and a planarizing surface of the circular polishing pad, a polishing pad conditioner for improving conditions of the planarizing surface of the circular polishing pad, etc. The CMP apparatus may also include an endpoint detector for detecting an endpoint of the CMP process.
The slurry is a carrier including abrasives and chemical materials used for polishing the surface of the semiconductor substrate. A polishing rate is an important variable in the CMP process that uses the slurry. The polishing rate may be determined in accordance with the type of slurry used in the CMP process. One factor in determining the polishing rate in the CMP process may be the diameter of the abrasive in the slurry, which may be about 10 Å to about 1000 Å. The hardness of the abrasive may also be used in determining the polishing rate in the CMP process. For instance, the hardness of the abrasive may be substantially equal to that of the surface of the semiconductor substrate.
A plurality of grooves in which the slurry flows is formed in concentric circles at the planarizing surface portion of the circular polishing pad. A plurality of micro pores is also formed at the planarizing surface portion of the circular polishing pad to receive the slurry therein.
The circular polishing pad is classified into two groups. One is a soft circular polishing pad and the other is hard circular polishing pad. The soft pad is a felt pad including urethane. The hard circular polishing pad is a porous urethane pad.
In a case where the semiconductor substrate is polished by a CMP process using the circular polishing pad and the slurry, micro pores are often filled with byproducts that are generated during the CMP process. Thus, a conditioning process for removing the byproducts from the micro pores may be required. The conditioning process may be performed simultaneously with the CMP process. Alternatively, the conditioning process of the circular polishing pad may be independently performed after the CMP process.
As an example of the circular polishing pad conditioner, a convex shaped polishing pad conditioner including nickel alloy is disclosed in U.S. Pat. No. 6,325,709 B1 issued Nanda, et al. Diamond abrasives attached to a lower face of the polishing pad conditioner contact a planarizing surface of a circular polishing pad.
In addition, a polishing pad conditioner comprising a conditioning element that includes a body and a bonding medium composed of nickel or, another metal, wherein the nickel layer is attached to a lower face of the body and diamond particles attached to a lower face of the bonding medium is disclosed in U.S. Pat. No. 6,361,413 B1 issued Skrovan.
The polishing pad conditioner for performing the conditioning process includes a conditioning disk. The diamond particles are attached to a lower face of a conditioning disk. The lower face of the conditioning disk contacts the planarizing surface of the circular polishing pad. The conditioning disk is then rotated and moved across the planarizing surface of the circular polishing pad during the conditioning process, thereby improving conditions of the planarizing surface of the circular polishing pad.
As a diameter of a wafer that is used as a semiconductor substrate is increased, a diameter of the conditioning disk is also increased. However, although a conditioning rate of the circular polishing pad is increased in proportion to an increase of the diameter of the conditioning disk, a pad wearing uniformity may decrease. In contrast, although the pad wearing uniformity is increased in proportion to a decrease of the diameter of the conditioning disk, the conditioning rate of the circular polishing pad may also decrease. Accordingly, to overcome the above-mentioned problems, an improved polishing pad conditioner is required.